The present invention relates to a method of formation and installation of a floating bridge including a superstructure supported by a number of prefabricated pontoons.
Several embodiments for floating bridges are previously known. In their simplest form, such bridges have a continuous single pontoon floating in the sea and a road structure is positioned directly on top of such single pontoon. Such floating bridges may, subject to incidental natural circumstances, represent an ecological problem in that they constitute a barrier hindering the natural replacement of surface water. Further, currents and waves may create large lateral loads on such floating bridge structures.
A floating bridge therefor preferably should be made with a freely extending superstructure which is supported by separate pontoons, so that the demand for strength and buoyancy is met, while at the same time the desired replacement of surface water is not hindered by any substantial degree.
The formation and installation of such a floating bridge may, however, represent a difficult problem, in that a very large crane capacity will be required in order to lift large prefabricated sections, the minimum length of which must be equal to the distance or space between pontoons, and the pontoons must be correctly positioned along the water surface.
From traditional bridge building technology is known a method whereby a superstructure is produced continually, but sectionally, in a stationary production site that is situated ashore at one of the shore fundaments, and whereby the continuously produced superstructure is transported or pushed gradually out into the water, whereat it is supported on prefabricated mutually spaced columns mounted on the sea bottom. The superstructure is pushed out along the respective columns until the other, opposite shore fundament has been reached.
Such method for building a traditional bridge with ground support is not readily transferable to the task of building a floating bridge, especially not in locations with tidal water variations, because a production plant positioned ashore and able to carry out a pushing of the bridge superstructure out onto, for instance, floating pontoons will create and impose too large vertical movements and thereby loads on the structure as a whole. The task of ensuring a secure positioning of the floating pontoons during the transportation or pushing operation of the bridge superstructure will also cause serious problems.